<b>Effect of salinity and temperature on metamorphosis rate to Protozoea and larval quality of <i>Litopenaeus vannamei</i></b>

Abstract

Temperature and salinity are two of the environmental factors that most affect the growth and survival of aquatic organisms. In order to estimate the optimal levels of salinity and temperature for the metamorphosis from nauplii to protozoea I stage of Litopenaeus vannamei, two separate experiments were carried out to evaluating the metamorphosis rate and larval quality. The salinity levels tested were 29, 31, 33 and 35 and temperature 25, 30 and 35 ° C. The data were subjected to one-way ANOVA (significance level 5%), followed by the Tukey test to compare means. There were no significant differences between the percentages of metamorphosis under the different levels of salinity and temperature tested (p>0.05). The quality of the larvae was not affected by salinity within the range tested, but was significantly lower (p<0.05) at a temperature of 35oC than under other treatments. Thus, the range of salinity from 29 to 35 was considered suitable for metamorphosis of nauplii, but the interval of temperatures from 25 to 35° was not considered ideal. This because the lowest level tested increased the time of development from nauplius to protozoea I and the highest caused the expansion of the chromatophores of the larvae, indicating a stress condition.